The objective of this project is to investigate local control of bone differentiation by extracellular matrix components. We have established in previous work the experimental model of matrix-induced cartilage and bone development and mineralization. Projects currently under investigation are: 1) the mechanism of action of extracellular matrix components on bone induction; 2) homology of bone inductive proteins from various species; 3) influence of experimental rickets on bone induction; 4) influence of estrogen and progesterone on bone differentiation; 5) influence of viruses on local bone formation; 6) influence of irradiation on bone formation; and 7) biosynthesis and fate of proteoglycans in cartilage and bone.